Short answer: A crossbite is when, with the jaw closed, some of the upper teeth sit inside the lower teeth when they should sit outside. It can occur in the side teeth (posterior) or the front teeth (anterior). It is treated mostly with palatal expansion appliances in children, and with braces, clear aligners or, in some cases, surgical support in adults; the method is determined at the exam.
A crossbite is the condition in which, when you close your mouth, some of the upper teeth sit inside the lower teeth rather than outside. In a normal bite the upper teeth slightly cover the lower teeth; in a crossbite this arrangement is reversed in the area of one or several teeth. It can involve a single tooth, or an entire side section or the front teeth. In this article we explain in general terms how a crossbite is recognized, why it occurs and which treatment options come up in children and adults. A personalized plan is always determined at an orthodontic exam.
How is a crossbite recognized?
Look at your teeth in the mirror while clenching: if you see that the upper back teeth meet the inner surface of the lower teeth rather than the outer surface, there is a possibility of a crossbite. In children, the clues families notice are usually the jaw sliding to one side as it closes, one side of the face looking different from the other, favoring one side when chewing, and the upper front teeth sitting behind the lower teeth. In adults, a feeling of an awkward bite, a habit of chewing on one side and wear on some teeth may stand out. A definitive diagnosis is made only with a clinical exam, intraoral images and, if needed, an X-ray examination.
What is the difference between posterior and anterior crossbite?
The difference is the region of the mouth where the problem is seen. A posterior crossbite is seen in the side and back teeth (premolars and molars); it is mostly related to the upper jaw being narrow relative to the lower jaw and can be one-sided or two-sided. In an anterior crossbite, the front teeth are affected; the upper incisors sit behind the lower incisors. This picture sometimes stems only from tooth inclination and sometimes from the relationship between the jawbones. Because the two types require different planning, telling them apart is the first step of treatment. For an evaluation from the clear aligner perspective, you can also look at our page on clear aligners and crossbite.
Why does a crossbite occur?
A crossbite does not have a single cause; heredity, jaw development and habits can play a role together. Insufficient widening of the upper jaw is one of the most common causes. Prolonged pacifier use and thumb sucking, mouth breathing, the position of the tongue, and early loss or late shedding of baby teeth can also affect the bite. Deviations in the eruption direction of permanent teeth, lack of space in the dental arch and an inherited jaw structure are other factors. In conditions such as nasal obstruction that leads to mouth breathing, the orthodontist may need to cooperate with an ear, nose and throat doctor if necessary. You can find options that help in giving up habits in our article on habit-breaking appliances.
What happens if a crossbite is not treated?
Not every crossbite carries the same risk, but in some cases left untreated, problems can become more pronounced over time. In children, the jaw sliding sideways as it closes can lay the groundwork for asymmetric bone and facial development. Uneven wear on the teeth, a tendency toward gum recession, reduced chewing efficiency and strain on the jaw joint muscles may be seen. For this reason, the presence of the problem requires the doctor's case-by-case evaluation; there is no rule that the same outcome will occur in every case. On the other hand, in cases noticed early, it is often possible to proceed with simpler and shorter interventions.
What is evaluated at the exam?
At the first visit, the doctor first examines the bite both in the mouth and on the face. Whether the jaw slides sideways as it closes, the alignment of the midlines, the inclination of the teeth and the width of the dental arches are evaluated. If deemed necessary, a panoramic X-ray, a lateral cephalometric film or three-dimensional imaging may be requested. In children, baby tooth loss, the eruption status of permanent teeth and habits are also asked about. By evaluating this information together, it is determined whether the problem is dental or skeletal in origin, and the treatment options, the possible process and the frequency of check-ups are discussed with the patient or parents.
How is a crossbite treated in children?
The main advantage of treatment in children is that the suture in the middle of the jawbones is still suitable for opening. In a posterior crossbite, the most commonly used methods are fixed or removable expansion appliances that widen the upper jaw slowly or rapidly. We covered this subject in detail in our article on the rapid palatal expander (RPE). In an anterior crossbite, small appliances that move the front teeth forward or devices that guide development are mostly planned. The timing of application is determined by the child's stage of development; for this reason, the first orthodontic exam at around age 7 is important. In suitable cases, clear aligner solutions for children can also be evaluated; for details, you can look at the page on Invisalign First for children.
What are the crossbite treatment options in adults?
In adults, because the jawbones have completed their development, treatment is shaped by whether the problem is dental or skeletal in origin. In mild cases of dental origin, the inclination of the teeth can be corrected with fixed braces or clear aligners. Where bone narrowness is marked, expansion methods supported by mini-screws or surgically assisted expansion may come up. If the discrepancy between jaw sizes is larger, jaw surgery together with orthodontics may be needed; for this, you can look at our article on orthognathic surgery. The page on Invisalign for adults can also be useful for an overview of adult orthodontics. We described the limits of jaw expansion in adults in our article on jaw expansion in adults.
Can clear aligners correct a crossbite?
In carefully selected cases, clear aligners can contribute to correcting a crossbite; however, they are not suitable for every case. In mild and moderate crossbites caused by tooth inclination, it may be possible for the aligners to move the teeth in small steps. In cases where bone narrowness is the main issue, clear aligners alone are often not enough; an expansion appliance, braces or surgical support may be needed. At our clinic, clear aligner treatment is carried out only with Invisalign, and which method is suitable is decided after a digital scan, photographs and the necessary imaging. For general information, you can look at the page on clear aligner treatment.
Is the corrected bite maintained after treatment?
Maintaining the corrected bite is an inseparable part of treatment. After expansion, a period of waiting is allowed for the newly formed space in the bone to mature, and then a retention plan is applied. Because teeth tend to return to their old positions after treatment ends, retainer use should be continued for the period and in the manner the doctor recommends. For details, you can read our page on the retainer after treatment and our article on retention after jaw expansion. Because treatment time and results vary from person to person, it would not be right to give an exact time; the estimated time is shared after the doctor's exam.
What should you do if you suspect a crossbite?
If you suspect a crossbite for yourself or your child, it is helpful to schedule an orthodontic exam without waiting for the symptoms to progress. In the evaluation at our clinic in Park Oran Ofis, Çankaya, the bite, the jaw relationship and, if needed, imaging are examined together; the treatment options and the process are explained to you after the exam. Cost information is also communicated in writing after the exam and planning. For an appointment, you can use our contact page.
Frequently asked questions
Does a crossbite correct itself?
In most cases it is not expected to correct itself. Posterior crossbites due to skeletal narrowness in particular become established over time. For this reason, the doctor's evaluation is recommended.
At what age should a crossbite be treated?
The age for treatment varies by case. In children, the developmental period provides an advantage for expansion; treatment is also possible in adults, but the methods are different. An orthodontic exam determines the most suitable time.
Can clear aligners be used for a crossbite?
They can be used in suitable cases caused by tooth inclination. If bone narrowness is marked, an expansion appliance, braces or surgical support may be needed. The decision is made at the exam.
Does a crossbite affect the jaw joint?
In some people, a bite discrepancy can contribute to strain on the chewing muscles and the joint. However, not every crossbite has the same outcome; the evaluation is made case by case.